View finder centering device for photographic apparatus



March 25, 1952 M. N. FAIRBANK 2,590,154

VIEW FINDER CENTERING DEVICE FOR PHOTOGRAFHIC APPARATUS Filed Aug. 11, 1948 2 SHEETSSHEET 1 FIG.

.JIIIIAIIIIJIIIIIIIIIII Patented Mar. 25, 1952 VIEW FINDER CENTERING DEVICE FOR PHOTOGRAPHIC APPARATUS Murry N. Fairbank, Belmont, Mass., assignor to Polaroid Corporation, Cambridge, Mass, a corporation of Delaware Application August 11, 1948, Serial No. 43,680

3 Claims.

This invention relates to photography and more particularly to novel view finders for use on handheld cameras.

. A principal object of the present invention is to provide an improved view finder of the direct sighting type having an improved construction which makes this view finder cheap and simple to manufacture.

Another object of the invention is to provide an improved viewfinderoi the above type wherein "a plurality of viewed-image-defining elements are provided and the various elements are so arranged as to permit the folding thereof into an inoperative position, the folding being effected in an extremely simple manner.

.Still another object of the invention is to provide a folding view finder of the above type having twov optical elements wherein the two elements thereof are brought into folded position by engaging only one of the two elements.

. Still another object of the present invention is :to provide a camera having a view finder of the above type and an improved means for centering a viewed scene and for correcting for parallax between the view finder and the lens system of the camera at close ranges of use of the camera.

These and other objects of the invention will in'part be obvious and will in part appear hereinafter.

;The invention accordingly comprises the apparatus possessing the construction, combination of elements and arrangement of parts which are exemplified in the following detailed disclosure, and-the scope of the application of which will be indicated in the claims.

Fig.'1a is a diagrammatic, fragmentary, en-' larged, sectional view of the view finder of Fig. 1, the section of Fig. 1 being taken along the line .Fig. 2 is a diagrammatic, exaggerated, fragz-mentary, sectional view of Fig. 1c taken along the line 2,2; 2:, Fig. 3 is a fragmentary, sectional view similar .to Fig. 1a with the parts of the view finder moved .to half-closed position; and

- Fig. 4 is an exaggerated, enlarged, sectional view .of' the centering means constituting a part of the invention. v

In general this invention relates to direct sighting view finders of the type wherein a plurality of viewed-image-defining elements are arranged along a sighting axis. In a preferred formof the invention two optical elements are provided, these elements comprising frames or masks whose edges define a field of view and the sighting axis. In :3 preferred type of finder the optical elements provide a reversed Galilean telescope, one optical element including a rear lens having positive powerand the other optical element including a front lens having negative power.

One feature of this invention is directed to the provision of improved means for mounting the two optical elements of the view finder on the camera so that they may be readily folded close to the camera, when not in use, to prevent damage thereto during handling of the camera. Another feature of the invention is the combination, with view finders of this type, of an improved means for centering the viewed image and for correcting for parallax of the view finder with respect to the camera lens.

In one preferred form of the invention ther is provided a suitable holder for one of the lenses of the view finder, this holder preferably serving as a protective housing for the two lenses of the view finder when the view finder is in closed position. A suitable holder is also provided for the other lens and means are included for maintaining the two lens holders in spaced relation, when in their operative position, so that the axes of the two lenses are aligned. In a preferred form, means are provided for moving one of the lenses from a position where the axes of the two lenses are in alignment to a position where the second lens underlies the first lens with the holder for the latter lensconstituting a housing for maintaining both lenses in a closed position. In this preferred type of arrangement, there is provided an operative connection between the holder for the first lens and the holder for the second lens so that, upon movement of the first lens holder to closed position, the second lens holder is folded into superposed. relation beneath the first lens holder.

In the preferred form of the invention this operative connection includes a supporting arm for the second lens holder, this arm in turn being pivotally connected to the first lens holder.' This supporting arm maintains the second lens in alignment with the first lens when the view finder isopened and is arranged to be pivoted, as a unit, with the first lens holder. As the view finder is closed, by pivoting the first lens holder, the supporting arm moves the second lens holder towards ment of the second lens holder which has a. greater angular speed than the angular speed of This. higher pivotal speed of the second lens holder pivotal movement of the first lens holder.

continues long enough to permit a folding of the second lens holder underneath the first lens.

holder as the latter is brought to closed position. For maintaining the various elements of the view finder in operative relationship with each other,

several spring elements are preferably provided; One of these springs maintains the supporting arm inproper. relation to. the first lens holder and another. spring maintains the secondjlens holder in proper relation tothe supportingarm. A third spring element maintain the first lens. holder in eithenclosedoropen position.

Referringnow to Figs.71,,, la and,2',', there is is ;shown one preferred j form of the invention as ap'plied to,ar hand-ih'eldj camera. In these figures, like numbers refer. to like-elements in each of the respective figures and Ill'represents the camera. b'ody having, the. usual bellows l2 connectedto a lens and;:shutter 'housingschematicallyindicatedat l4: The shutterhousing is ;preferably carried'by a front TdOOI member l5; having a focusingtrack H thereon: Suitablymountedion the shutter housing i 4 is a view-i finder centering device I6 comprising a relatively deformable element having a: front sighting ,mark', comprising ,a'ball, l8, on the end thereof; The view finder" is generally indicated at being shown in the open position'in Figs.

11and1a, and "in the half -closed position in Fig.

3." For securing the view finder 2t] to-the camera body, there is ,shown a securingmeans 22 comprisinga base plate fastened,v such as by'means of rivet s -24, to the camera body -I 0:

The front-lens 26 ofthe view finder is preferably a negative :power lens and the rear-lens 28gis preferably apositive power lens. The front lensy-Zdis-"carried by;a lensholder 30 and-the rear: lens, 28- is carried by a second holder 32. Aimaskportion 3 I of the front lens holder 30,

and, -a mask--portion'33, of "rear lens holder '32,

define-thelimits of-the field viewed through the turd-lenses: A pair of-springelements 34, se-

cure'd tdbase plate (22"bYII1E2iDSS11Ch' as rivets are provided for mounting ;the front lens holder 30; At *the free (left) 'end' of the spring elements 34; there is held a pivot'pin 38, pin'38 extendingthrough-journal holesdo (Fig.2) in the lside walls of the front lensh0lder-30. A pair'p f planar bearing surfaces 42 and 44 are provided jon, the lower endof holder-30; surface 42; jgbeing substantially parallel to the lens axis and surface 44 being substantially normal to i pin48l} Pivotpin 48. extends through a'pair' of journal holes -50.,(Fig. 2)' in'.a pairof side Walls 52 associated with the rear lens holder 32. The outer end of finger 54, carried by the end of supporting arm 46, serves as a lug which is adapted to bear on a bottom portion 56 of the rear lens holder 32. For rotating rear lens holder 32 in a counterclockwise direction around pivot pin 48, there is provideda pair of down- Wardly extending skirts 58 which are adapted to engage a pair of studs 59, preferably constituting a part of base plate 22, when the arm 46 is lowered.

For'normally urging the arm 46 in a clockwise direction around pivot pin 38, and into engagementwith atop portion 60 of the planar surface member 44, there is provided a coil torsion spring 62.' This coil spring 62 is coiled around. pin 38, one end bearing on arm 46 and the. other end bearing on holder 30 and tending to maintain arm 46 in the position shown in Fig. 1. For normally rotating rear lens holder 32 -in-'a-clockwisedirection around pivot pin-48, untilportion-56 of the holder 32-engage's:the -lug portion of finger 54, there is pr0vided-a second torsion spring 64. Spring is preferably coiled around pin 48, one end bearing'on arm 43and the other end bearing on holder- 32. These two springs 62 and; inaddition to" springs 34, maintain the elements in the positiongshownat Fig: 1..

In theiclosing operation of the view' ifinder shown in Figs. 1 throughfi, the-front lens holder 304s pushed in a clockwise direction around pivot pin 3B;- As thelens holder 33 commences to rotate, pivot pin 38 is moved upwardlydu'e to the fact that the corner- 43 bears onthe-base plate 22 At the-same time, the top 60 of 'thesurface de'fining member44 also drops; Therais'ing of the pivot pin '38 i and the dropping of portion Gil allows the spring t2 to :rotate arm "46 rapidly towards the camera body? l0. As arm' '46' 'rotates downwardly, the downwardly extending skirts 58, on the rear lenslholder 32,- engage the studs 59-, thus rapidly irotatihgtrear lens holder 32 in a. counterclockwise direction aroundpivot pin against the force of coil"springf64;-- This movement of the various elements of :theview finder is shownsmost clearly. in'Figr. 3 wherein the rear'le'ns holder 32 has begun to' rotate around its pivot point 48. Continued rotation ofthe elementspast the-position shown inFig. 3 causes the J =lenssh'older I 32 -.:to' rotate completely under "the lens holder 30," lens holder 30-engaging lens holder :32 Jinxthe;:latter part of the travel-and maintaining lens "holder 32 in its .folded: condition. During the latter .porti0n=ofythe travcl of lens holder 30 down into itsclosedposition -bearing surface 44 hasbeen brought into engagement with the base plate 22.' When surface-44"is fiat against plate 22", the :spring' 1 elements 34 maintain .lens: holder. 30 tightlyi'in place, spring Felements 34 being strong enough to resist the opening forces of springs 62 and '64.:

the skirts 58 are clear-of the studs 591 As the front lens holder 30"sWingsinto-the position shown, the top portion 60, offsurface defiing member 44, lifts arm 46 to'move it -t'o the position shown in Fig. 1a. Meanwhile, rear lens holder 32 has been rotated clockwise until the portion 56 thereof engages the finger 54 carried on the end of the arm 46. When the elements of the 1 view finder have been moved into the position of the supporting column is is preferably coplanar with the view finder axis and the camera lens axis. It supports the ball l8 sufiiciently far in front of the view finder so as to allow this ball to be sharply in focus to an observer looking through'the view finder, the ball indicating the center of the viewed image. As shown most clearly in Fig; 4, the centering means I6 is so made as to be relatively easily deformable in any direction throughout substantially its whole length; This centering means is preferably formed of a tightly coiled closely wound helical spring 10. This spring is preferably so tightly wound that it has the highest possible initial tension. Thus the coils of the spring tend to squeeze themselves together so that the spring element 10 normally extends in a straight line, as shown, but may be easily deformed by external forces. Spring element 10 is mounted on a threaded stud l2, stud 12 being secured to a partially cylindrical rod 14. Rod 14 is secured, by means of a spring clamp 16, to one of the arms 18 which hold the shutter housing in upright position. It should be noted that a flat portion 15 on the rod 14 preferably bears against a stud securing the arm 18 to the housing 14, thereby holding the centering means in a position normal to arm 18. The resilience of clamp 15 permits rotation of rod 14 around its axis so that the centering means It may be folded along arm 18 when desired. On the outer end of this spring element 10 there is provided a second stud 80 carrying the ball [8 on the extremity thereof. Spaced inwardly on the ball l8, and also carried by the stud 80, is a collar 82.

In a preferred form of arrangement of the above elements of the invention, the view finder axis is substantially parallel to the camera" lens axis. The centering ball I8, carried by the centering means i5, is spaced slightly inwardly of the view finder axis towards the camera lens axis, thereby centering the view finder image for objects which are photographed at a distance of about 40 feet from the camera. This ball I8 is used for objects down to about 8 feet. For objects less than about 8 feet from the camera, the camera user centers the view finder image by means of collar 82, thereby approximately correcting for parallax due to the shorter distance of focus. While the centering indicia are shown in the form of a ball and collar, numerous other combinations of indicia may be employed and a plurality of collars can be used where absolute accuracy is required. In those cases where it is desired not to use the centering means IE, it can be folded down along the arm 18 where it will be completely out of the field of view of the view finder. 5.;

When the camera is folded, the shutter housing I4 is moved into the camera body and the centering means l6, which may be extending outwardly in the position shown in Figs. 1 and 4, engages the edges of that portion of the camera body adapted to receive the bellows and the shutter housing. Due to the ability of the coil spring to be deformed in all directions, through substantially its whole length, the centering means is drawn into the camera body with no difficulty, bending around any obstruction encountered. The camera cover 15 is then closed, it being unnecessary to touch the view finder centering mea s l6 during the closing of the camera. When the camera is opened, as soon as the shutter housing I4 is free from the camera body, the coil spring 10 may be grasped so as to move the stud 12 to the vertical position in Fig. 4. In those cases where the hinged connection 14, I6 is omitted, the resilience of the coil spring I0 allows this coil spring to immediately straighten itself out to the position shown. Aonther advantage residing in the flexibility of the coil spring, forming the supporting column I6, is its freedom from the possibility of damage due to catching on the user's clothes or the like. If this should happen, the supporting column l6 readily bends and then stlfiightens itself out as soon as it is disentangled.

While a preferredform of view finder has been shown in Figs. 1 through 3 above, numerous modifications thereof can be made within the scope of the invention. For example, the position of the lens holders canbe reversed so that lens holder 30 is at the rear of the camera instead of at the front as shown; In this case lens holder 30 would carry the positive lens 28 and lens holder 32 would be at the front of the camera, holding negative lens 26. Equally, numerous modifications may be made in the specific form and shapes of the stampings and other parts from which the view finder is formed. For example, the securing plate 22 may be eliminated, in which case the rivets 36 may hold the spring elements 34 di rectly on the camera body. With such a modification, the bearing surfaces 42 and 44, associated with lens holder 30, will bear directly on the camera body and the cam stud 59 may be a part of the camera body ID or may be a separate stud suitably secured thereto. Equally, leaf springs or other types of springs can be substituted for the helical springs 62 and 64, and other types of hinges, supports, and stop lugs may be employed without departing from the scope of the invention.

Since certain changes may be made in the above apparatus without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A view finder centering device adapted to be mounted on a camera having an eye level view finder and to be observed through said view finder when sighting on an object to be photographed, said centering device comprising a resilient columnar member which normally extends in a straight line and which is substantially universally bendable from its straight condition upon the application of a deforming force thereto but which, due to its resiliency, is returnable to said straight condition upon the removal of said force, said columnar member being formed of a tightly coiled helical spring having a high initial tension, hinge means connected to one end of said columnar member and pivotally securing said centering device to said camera, the end of said columnar member away from said hinge means being unsupported and free, and at least one sighting membercarried by said columnar member adjacent said free end of the columnar member, said sighting member providing means for locating 7 the centercf the field of view observed through said'view finder.

' '2'. A view finder centering device as defined in claim 1 wherein said columnar member has one sighting member adjacent the free end ofthe columnar member and at least a second sightmg member carried by the columnar member at a location adjacent said first sighting member fand between the first sighting member and said nar member is fixed and includes means which assist in holding said columnar member against accidental displacement from an operative'position to an inoperative position.

NIURRY N. FAIRBANK.

REFERENCES CITED ,The following references are of record in the file of this patent! UNITED STATES PA'I'ENTS Number 15 Number Name Date Springsteen Nov. 1, 1898 Folmer' Apr. 11, 1911 Ruttan et a1 May 6, 1913 Becker Apr.'4, 19-16 Stout Apr. 2,1918 Wittel Nov. 7,1933

' Mihalyi June 9, 1936 Bernack July 12, 1938 Leitz' May 9,1939 Walker Aug. 20, 1940 FOREIGN PATENTS 7 Country Date Great Britain Of 1910 Great Britain Of 1911 

